The Thomas B. Fordham Institute looked at it and came up with some interesting findings.
Writing for the Fordham Institute, Seth Gershenson discovered that:
“Utilizing student-level data for all public school students taking Algebra I in North Carolina from 2004–05 through 2015–16 (including course transcripts, state end-of-course exam scores, and ACT scores), the study yielded three key findings:
“~Although many students get good grades, few earn top marks on the statewide end-of-course exams for those classes.
“~Algebra I end-of-course exam scores predict math ACT scores much better than do class grades.
“~During the decade studied, grade inflation was more severe in schools attended by affluent students than in those attended by lower-income pupils.”